How to Select Dust Filter Bags for Working Conditions in Different Industries?

The selection of filter media is a comprehensive decision based on the characteristics of the dust collector system and on-site working conditions. Key factors to be prioritized include: temperature, relative humidity and corrosivity of dust-laden gas, dust particle size, hygroscopy, deliquescence and abrasiveness. The working condition characteristics of different industries and the key points for filter media selection for dust filter bags are as follows: 

(1) Blast furnace gas purification in iron and steel plants Dust pollutant emissions are large in volume and wide in coverage; the types of dust pollutants are complex with diverse characteristics; dust particles are fine and highly adsorptive; dust emissions are paroxysmal with significant fugitive discharge; dust pollutants have rich components and are recyclable for comprehensive utilization. The filter media shall have a temperature resistance of above 200℃, featuring high strength, good toughness, easy ash cleaning, water and oil resistance, antistatic properties, corrosion resistance and stable performance. Recommended options: Synthetic fiber filter media such as aramid, P84 and PTFE fibers; composite filter media of glass fiber and synthetic fiber (e.g. Flumex, glass fiber-P84 composite filter media); surface-coated and membrane-laminated filter media of the above two types. 

(2) Kiln tail dust collection in cement plants The flue gas temperature at the kiln tail is high (around 350℃) with large fluctuations; the dust concentration in flue gas is high, with a large amount of high-temperature decomposed components and fine powder; the relative humidity is high, and the flue gas dew point temperature varies with different cooling methods. Filter media selection shall first consider flue gas characteristics (temperature, relative humidity, corrosivity, oxidants, etc.), as well as dust concentration, dust removal efficiency, system resistance, dust stripping rate, and the warp and weft breaking strength and elongation of the filter media. Recommended options: Glass fiber cloth + PTFE membrane-laminated filter media for most applications; P84 or Nomex needle-punched felt with impregnation surface treatment for partial applications. 

(3) Dust collection for coal-fired boilers in thermal power plants The discharged flue gas has a high temperature and high contents of SO₂, NOₓ and O₂; the dust concentration is high; retrofitting projects require low-resistance filter media. The filter media shall be temperature, acid-alkali, oxidation and hydrolysis resistant, and used at a temperature 10℃ above the acid dew point and below the maximum allowable temperature. Needle-punched felt is recommended with a basis weight of 530~550 g/㎡. Recommended options: PPS and PPS+P84 needle-punched felt (P84 content around 20%), PPS and PPS+P84 gradient needle-punched felt, or PTFE gradient composite needle-punched felt. 

(4) Industrial carbon black production in chemical industry Carbon black production involves high temperatures and corrosive flue gas; the flue gas contains a large amount of fine particles and flammable gases; the filtered tail gas is to be recycled for comprehensive utilization. The filter media shall be high temperature and corrosion resistant, with a long service life, low system resistance, strong ash cleaning capacity and high dust removal efficiency. Recommended options: Glass fiber needle-punched felt or Nomex high-temperature resistant needle-punched felt; bulked glass fiber cloth or continuous glass fiber cloth; glass fiber cloth + PTFE membrane-laminated filter media.

 (5) Municipal solid waste incineration Flue dust is highly hazardous with strict pollution control requirements; the flue gas has high moisture content and a high dew point temperature; alternating high and low flue gas temperatures exist; the flue gas is highly hygroscopic; the dust particles are fine with low density; and the corrosivity is strong. Therefore, the filter media shall have a high temperature resistance up to 230℃, good hydrolysis resistance to adapt to high-humidity flue gas, strong corrosion resistance, excellent dust removal effect and a long service life. Typical selections by region: Japan adopts glass fiber cloth + PTFE post-treatment/membrane lamination, glass fiber cloth + ultra-fine PTFE spunlace felt; Europe uses PTFE needle-punched felt, PTFE+P84 composite needle-punched felt; China selects PPS needle-punched felt, P84 needle-punched felt, glass fiber cloth + PTFE membrane-laminated filter media and PTFE needle-punched felt.